Some aircraft and marine craft use turbo electric distributed propulsion (TeDP) systems for distributing electrical power from onboard generators, to one or more propulsors. Each propulsor may include a motor for driving a propeller or fans that spin at a certain speed so as to positively affect aerodynamic and hydrodynamic performance of the vehicle. The electrical power that drives each propulsor motor may come from a generator that is driven by a turboshaft engine.
When a TeDP system relies on a DC distribution system for distributing electrical power from an AC generator to one or more AC propulsor motors, the TeDP system may rely on dedicated inverters located at each propulsor motor that convert the output of the DC distribution system back to an appropriate amount of AC electrical power for powering the propulsor. Each dedicated inverter may suffer from an undesirably large mass and weight. Additionally, each rectification to DC and the dedicated inverters introduce undesirable losses into the system which leads to system inefficiency and increase thermal loads.
Some TeDP systems try to avoid the large mass and weight attributed to dedicated inverters by driving each propulsor motor, directly, with the variable frequency, AC power that comes from the generator. For example, some TeDP systems forgo the use of a DC distribution system and associated inverters and instead, rely on a variable frequency, AC microgrid that distributes electrical power to the propulsor motors, directly from the turbo generator. Despite saving size and weight, powering propulsor motors directly using an AC microgrid distribution system may come with challenges. For example, each propulsor motor must maintain speed synchronicity with the generator, both during start-up, and during transient loading of the propulsor. If synchronicity between the generator and propulsor motors is lost (e.g., due to a torque spike), the TeDP system may be unable to drive the propulsor fans or propellers and the aircraft or marine craft may lose thrust.